Jet propulsion apparatus



June 25, 1968 K. P. HALL 3,389,558

JET PROPULSION APPARATUS Filed Dec. 15, 1966 4 Sheets-Sheet l KIMBALL June 25, 1968 K. P. HALL JET PROPULSION APPARATUS 4 Sheets-Sheet 2 Filed Dec. 15, 1966 L L A H R L L A 8 I June 25, 1968 K. P. HALL JET PROPULSION APPARATUS 4 Sheets-Sheet 3 Filed Dec. 15. 1966 KIMBALL P. HALL June 25, 1968 K. P. HALL JET PROPULSION APPARATUS 4 Sheets-Sheet 4 Filed Dec. 15, 1966 INVENTOR. K IMBALL P. HALL United States Patent 01 iice 3,389,558 Patented June 25, 1968 3,389,558 JET PROPULSION APPARATUS Kimball P. Hall, Shoreham, N.Y., assignor to Hall Marine Corporation, Princeton, N.J., a corporation of New Jersey Filed Dec. 15, 1966, Ser. No. 601,942 9 Claims. (Cl. 60-221) ABSTRACT OF THE DISCLOSURE The present invention relates to a shrouded impeller type, hydraulic jet propulsion unit and attachment apparatus for converting a propeller drive to a propulsion system.

The present invention relates to improvements in jet propulsion apparatus and is concerned more particularly with attachment apparatus to be substituted for the propeller of a rnarine motor whereby to convert the same from a propeller drive to a jet pump propulsion system.

A very important advantage of jet pump propulsion, particularly in recreational power boating, arises from the elimination of the high speed rotating bare propeller. Safety for swimmers, water skiers, skin divers is greatly increased, the danger of snagging and snarling tow ropes and lines is greatly reduced and the boat operators responsibility is relieved. Substitution of :a jet pump for a propeller also improves slow trolling performance of the engine.

The principal object of the present invention is to provide a jet propulsion unit which is adapted easily to be substituted on the drive shaft of an outboard or inboard marine motor when the propeller is removed and which will require for its operation no modification of the motor cooling system, exhaust gas flow or any internal gearing. Further, it will require no alteration of the steering wheel or cable arrangement or throttle or gear shift linkage arrangement for forward or reverse. Illustrative of the ease of installation of the jet unit after the propeller and its shear pin has been removed is the fact it is only necessary to secure the fixed portions of the unit to the conventional motor gear case seal plate and to secure the rotor to the motor shaft by another shear pin. Also, the unit may as easily be removed and the propeller replaced whenever desired.

Other objects and advantages will be apparent from the following detailed description taken in conjunction with the accompanying drawings wherein preferred embodiments of the principles of the invention have been selected for exemplification.

In the drawings:

FIG. 1 is a representation of a conventional outboard motor showing the jet propulsion unit of the present invention attached to the bottom portion thereof in place of the conventional propeller, it being understood, how ever, that the jet propulsion unit of the present invention is also adapted for attachment to inboard-outboard motors;

FIG. 2 is an enlarged rear end view of the jet propulsion unit shown in FIG. 1;

FIG. 3 is a sectional view taken on line 3-3 of FIG. 2 and looking in the direction of the arrows;

FIG. 4 is a sectional view taken on the line 4-4 of FIG. 3 and looking in the direction of the arrows;

FIG. 5 is a sectional View taken on the line 5-5 of FIG. 3 and looking in the direction of the arrows;

FIG. 6 is a sectional view taken on the line 6-6 of FIG. 3;

FIG. 7 is a sectional view taken on the line 7-7 of FIG. 4;

FIG. 8 is a view similar to FIG. 4 but showing a modified form of that part of the invention;

FIG. 9 is a sectional view taken on the line 9-9 of FIG. 8; and

FIG. 10 is a sectional view taken on the line 1010 of FIG. 8.

Referring more in detail to the drawings wherein like numerals refer to like parts, the outboard motor shown in FIG. 1 includes a conventional anti-cavitation plate 2, exhaust gas outlet 4, motor gear case 6 having a seal plate and skeg or the like 2. The jet propulsion unit of the present invention is indicated in its entirety by the numeral 10.

The jet pump device 10 comprises, as; best shown in FIG. 3, a shroud 12 having at its forward end a concentric mounting collar 14 carrying on its periphery a radial array of streamlined struts 16 and secured to the shroud 12 in any suitable manner such as by the screws 17. A runner or rotor 18 which includes a hub 20 and a series of propelling vanes 22 follows the mounting collar 14 and struts 16 within the shroud 12. A stator 24 having a streamlined afterbody 26 and a series of flow-straightening vanes 28 follows the rotor 18 within the shroud 12.

The shroud 12, rotor 18 and stator 24 and their respec tive parts may be formed by sand-casting or die-casting or in any other desired manner preferably of materials known to provide the required strength and seawater corrosion resistance.

The mounting collar 14 of the unit 10 is attached to the gear case 6 of the outboard motor concentrically of the drive shaft 30, after the propeller has been removed, by bolts 32 which are screwed into threaded holes in the after seal plate as usually provided by the engine manufacturer and normally serving as the point of attachment of a special puller tool for the seal plate. Of course, if such threaded holes are not present, they may readily be bored on the seal plate for this attachment purpose.

The rotor or runner 18 is positioned in axial alignment with the drive shaft 30 by a hub plate 3 4 and receiving hub 36 surrounded by a flexible liner 38 coaxially positioned by dowel pins 4-0 and a hub nut 42 in threaded engagement with the hub 36, as shown in FIG. 3. As also shown in FIG. 3, an annular bearing 44, either of the water lubricated or sealed type, is positioned in the afterbody 26 of the stator 24 for receiving the extended free end portions of the rotatable hub 36 and. shaft 30 which are interconnected by the shear pin 46.

When the parts are thus assembled the screws 17 are threaded into the peripheral extremities of the struts 16 of the mounting collar 14, either directly or through a surrounding ring structure, solidly to secure the unit 10 in axial flow alignment with the motor drive shaft. It will be noted that the unit provides for full directional control in forward and reverse just as with the original propeller and a forward facing intake scope for maximum propulsive efficiency.

In the modified form of mounting plate shown in FIGS. 8-10, 114 represents the concentric mounting collar and 116 the streamlined struts. In the modified form of mounting plate, the struts or spokes are greater in number, such as the eighteen shown in FIG. 8 as compared with the eight shown in FIG. 4 and under certain circumstances provide for greater protection particularly when the unit is used by swimmers or water skiers. The mounting collar 114 of the modified mounting plate may be secured to the after seal plate by the same bolts 32 as shown in FIGS. 3 and 4-.

It will be apparent in operation that water is scooped into the forward end of the concentric passage between the mounting collar 14 and the shroud 12, passing through the solid object protective struts 16. The inflowing water passes through the rotating runner or rotor 18 which accelerates the flow and imparts a spin to the stream. The

flow velocity is also accelerated by the tapered convergent rotor chamber formed by the shaped shroud 12 as particularly apparent from FIG. 3. The accelerated stream passes through the stator blades 28 which, by cancelling out most of the spin, convert angular momentum, otherwise lost, into useful thrust and then emerges from the open aft end of the shroud.

Thrust is imparted to the boat to which the motor is attached in accordance with the equation:

t n Q I g uut I In) where F=lbs. of thrust riz lbs. of water passing through the pump per second V =velocity of the jet leaving the pump in feet per second =velocity of water entering the pump in feet per second g=32.2 lb. ft./sec.

In this expression, when the boat is moving very slowly forward, V is an induced velocity due to suction effect of the pump, but at intermediate and high forward speeds V corresponds approximately to the forward speed of the boat.

It is to be understood that the present invention is not confined to the particular construction and arrangement of parts as herein illustrated and described but embraces all such modifications thereof as may come within the scope of the following claims.

I claim:

1. Jet propulsion apparatus for replacement of the propeller on the shaft of a marine motor having a gear case seal plate through which the shaft projects which com- 3 prises,

a shroud,

a concentric mounting collar including a radial array of struts carried by the shroud as its forward end,

a concentric stator including a radial array of flowstraightening vanes carried by the shroud as its after end,

a concentric rotor including a hub and a plurality of radial propelling vanes disposed within the shroud between the mounting collar and stator and adapted for connection to said shaft for rotation therewith, and

means for securing the mounting collar to said seal plate whereby fixedly to support the mounting collar, shroud, and stator coaxially of said shaft.

2. The apparatus of claim 1 wherein the marine motor is an outboard motor.

3. The apparatus of claim 1 wherein the marine motor is an inboard motor.

4. The apparatus of claim I wherein the seal plate is provided with threaded holes for a puller tool for the seal plate and the mounting collar is secured to the seal plate by bolt means engaged in said threaded holes.

5. The apparatus of claim .1 wherein the mounting collar and its struts are separate from the shroud and the mounting collar and its struts are secured to the forward end of the shroud after the mounting collar is secured to the seal plate and the rotor is connected for rotation to the shaft.

6. The apparatus of claim 1 wherein the rotor includes a hub plate, receiving hub and a threaded hub nut for positioning the rotor in axial alignment with the shaft.

7. The apparatus of claim 6 wherein a flexible liner surrounds the receiving hub.

8. The apparatus of claim 6 wherein the free end portions of the receiving hub and the shaft extend aft of said rotor and an annular bearing is positioned in the stator to receive said free end portions.

9. The apparatus of claim 7 wherein the free end portions of the receiving hub and the shaft extend aft of said rotor and an annular bearing is positioned in the stator to receive said free end portions.

References Cited UNITED STATES PATENTS 2,965,065 12/1960 Tinker 60--221 XR 3,114,239 12/1963 Aylor 115-16 XR 3,249,083 5/1966 Irgens 60221 XR CARLTON R. CROYLE, Primary Examiner. 

